I will hazard a prediction. When you are 80 years old， and in a quiet moment of reflection narrating for only yourself the most personal version of your life story， the telling that will be most compact and meaningful will be the series of choices you have made. In the end， we are our choices. Build yourself a great story.

质量不是选择；它是要求。

数学之美在于它能够连接看似无关的思想。

真正的朋友是很难找的。